The present invention relates to a method for operating an internal combustion engine.
More particularly, it relates to a method of operation of an internal combustion engine, in which the fuel is burned during a working stroke in at least one combustion chamber, a gas pressure which is generated during a working stroke in the combustion chamber is detected by a pressure sensor, and the plausibility of a measuring variable obtained form the signal of the pressure sensor is monitored.
Such a method is known on a market. A pressure sensor is provided in an internal combustion engine in at least one cylinder and measures the actually acting gas pressure in the combustion chamber of the cylinder. With the variables derived from the gas pressure, it is possible to obtain knowledge about the course and the quality of the combustion of the fuel in the combustion chamber. This knowledge can be used for an optimization of the control of the combustion engine, in particular with respect to the fuel consumption, the emission behavior and the running quietness.
The used pressure sensors are however extremely subjected to temperature and pressure loads. Therefore, a complex mechanical design is needed to uncouple an evaluating electronic unit of the pressure sensor from a receiver, which is arranged directly on the combustion chamber of the cylinder of the internal combustion engine. Therefore, it can not be excluded that such a pressure sensor fails. In order to recognize a failure, the plausibility of the signal of the pressure sensor is monitored. For this purpose, in the known methods rigid limiting values are defined, and when the signal is below or above the limiting value, a conclusion about an error of the pressure sensor is made. For example, a failure of the pressure sensor is recognized when the sensor signal during the operation of the internal combustion engine indicates zero volt.